XS650SK Carburetor Jetting Confusion

If your pilot jets really are #30's that should be way lean, unless maybe they're the wrong type. Two different types of pilots were used in the various 650 carb sets. You should use the type your carb set was designed for. Carefully examine your current pilots to determine which type they are. Which end the metering orifice is on will tell you that .....

Fp7VrJA.jpg


Uoaj1xt.jpg


The BS34s use BS30/96 pilots.
 
The air jet that Gary shows in his pic feeds the pilot circuit and can be used as another way to tune it, or I should say fine tune it. It doesn't have as big an effect as changing the pilot jet itself so using it, you can achieve richness levels in between pilot jet sizes. The parts diagrams often list it as a main jet because, well, it is. It is a standard Mikuni N102/221 type main jet, what's called a "small round" main, but in this case, it's used as an air jet and flows air.

XuTgyBl.jpg
 
$1.23 at Part Shark here.

If I use Partzilla, my recent experience says it will be March when I get my parts. Part Shark offer Priority Mail or UPS shipping. My current order is lost or detained by USPS. :(

Years ago, before I had internet or computer, I needed Chevron seals of the same style to overhaul my brake master cylinder to my 1966 Ford Thunderbird. I bought the required batch and put kits together for folks in the club. I can't really remember how I pulled that off, but I did.

Perhaps a story ..Of Thunderbird's I believe it was a 66
I am not sure what year this was ,But the Thunderbird was rather new.I believe a year or two.
In those days it was a rare car for anyone Here I don't believe more than 2 digits total sale in the Country.
Might even be . Under ten sold . More of a Sports star och Rock star to own .. such a car.
It was a Roadside Cafe Hamburgers and that stuff .With a gravel yard at front
I was about ten years at the time
The Ford drove up close to the entrance two very nice Looking girls high heels Jewelry Not very long skirts.( so much I did understand )
And a Young man .Unusually young to own that type of Automobile .
Dark Hair Elvis Look ..Normal looking no Tats no Muscles . Healthy looking.
No sports star look nor Rock star look.
There was also a small Child who was Whining and Complaining non stop
The man ordered his burger Sitting outside in the sun the girls tripping around

The Child non stop whining. Wanted to leave perhaps go home
Both front doors open i Looked inside some type of Rock and Roll Music.
There was the chromed foot on the gas pedal ..with toes. .
Child whining
Man trying to tell ... Gently we must to eat first then we leave ..A couple of times
Did not help ..continued and then the Young man straightened his back up after ca half the Meal
Told my father-- Dont get scared now we leave ..
Ahha whats going on now .. Nobody understood .. Certainly not me
In with the girls in with the child close the doors .. start the engine
AND THEN HE FLOORED IT Pedal to the metal ...
Wheel spun of course on the gravel ..Dust cloud blowing luckily to the other side .
Fish tailing and then when he hit the Asphalt continued spinning as if it was Mc Queen in Another Ford in Bullit
Yiiiiieeeee..e e more smoke .. Disappearing with a roar dust cloud slowly. setting
I stod there thinking aaaohhheee this is the real life ... this is how it is done .
Like a Movie scene except it was real.
Any nice Thunderbird Pictures. ??
 
your girl friend looks HOT Marty.

BS34 carbs
Throttle shaft seal Suzuki part # 13651-51010 SEAL
I replaced the butterfly shaft seals with these Suzuki seals they fit perfectly. Cost a dollar less than the Yamaha seal .....
https://www.partzilla.com/product/suzuki/13651-51010 5twins tip

BS34 mix screws 1mm thick x 3mm I.D. 5twins aug, 2017

float valve to carb body 1.5mm thick x 7.5mm I.D. o-ring http://www.xs650.com/threads/float-valve-seat-o-ring-size.15162/

Fuel line tee http://www.xs650.com/threads/fuel-t.7173/#post-74573
replacement fuel T approx. 2.37"L0.343"W 0.365" at o-ring -xjwmx

'81-on BS34 float bowl drain screw o-ring - 1.6 x 4.1 -5twins

Idle mixture screw assembly, Not sold for the XS650 BS34s. But, similar Mikuni BS carb mix screw is the same, complete, screw, spring, washer, o-ring.
https://www.partzilla.com/product/yamaha/12R-14105-00-00
 
If your pilot jets really are #30's that should be way lean, unless maybe they're the wrong type. Two different types of pilots were used in the various 650 carb sets. You should use the type your carb set was designed for. Carefully examine your current pilots to determine which type they are. Which end the metering orifice is on will tell you that .....

Fp7VrJA.jpg


Uoaj1xt.jpg


The BS34s use BS30/96 pilots.
As is usually the case, @5twins to the rescue! You nailed it. I have orifice at the top. I'll get the correct jets coming.
 
your girl friend looks HOT Marty.

BS34 carbs
Throttle shaft seal Suzuki part # 13651-51010 SEAL
I replaced the butterfly shaft seals with these Suzuki seals they fit perfectly. Cost a dollar less than the Yamaha seal .....
https://www.partzilla.com/product/suzuki/13651-51010 5twins tip

BS34 mix screws 1mm thick x 3mm I.D. 5twins aug, 2017

float valve to carb body 1.5mm thick x 7.5mm I.D. o-ring http://www.xs650.com/threads/float-valve-seat-o-ring-size.15162/

Fuel line tee http://www.xs650.com/threads/fuel-t.7173/#post-74573
replacement fuel T approx. 2.37"L0.343"W 0.365" at o-ring -xjwmx

'81-on BS34 float bowl drain screw o-ring - 1.6 x 4.1 -5twins

Idle mixture screw assembly, Not sold for the XS650 BS34s. But, similar Mikuni BS carb mix screw is the same, complete, screw, spring, washer, o-ring.
https://www.partzilla.com/product/yamaha/12R-14105-00-00
I went to The O-ring Store and stocked up. $7.99 for FedEx 2 Day shipping. Such a deal!
 
Another thing I found was no packing (o'ring) under the mix screws. :redface: :notworthy:
Are you sure? The (now disk shaped) o-ring (and often the shielding metal washer) can only be fished up out of the well by a tiny hook. Bend one up out of safety wire.
Second from left in this line up of special carb tools, cleaners.
wiper tools.jpg
 
There is no such thing as a mix screw.......Pilot screw allows more of the mixed air/fuel mixture into the throat of the car........if anything it would be a flow screw.......
View attachment 183948
I stand corrected, once again! :notworthy: There are no packings under the pilot screws.
 
Back
Top